


What if

by ViceCaptain



Category: Doctor Who, Sherlock (TV)
Genre: Crossover, M/M, filthy but full of feels, what about a foursome?
Language: English
Status: Completed
Published: 2012-11-13
Updated: 2012-11-13
Packaged: 2017-11-18 14:36:44
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 4,650
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/562127
Author URL: https://archiveofourown.org/users/ViceCaptain/pseuds/ViceCaptain
Summary: <blockquote class="userstuff">
              <p>Two simple words that you can spell in less than a second but that open billions of scenarios in anybody’s mind.</p>
            </blockquote>





	What if

**Author's Note:**

> well, first time for me to write a crossover. This was a lot of fun and so beautiful, putting together two of my favourite tv shows. My advise is, try it out sometimes, it's really good :D  
> (brace yourselves for some fluff at the end)  
> Set after [Someone thinks time is a straight line](http://archiveofourown.org/works/513924) (more or less, with some timey wimey tricks), it's not necessary to read it first, but it could help you to understand who is talking in the prologue.  
> Temporarly this would take place after "The Last of the Time Lords"

What if…

Two simple words that you can spell in less than a second but that open billions of scenarios in anybody’s mind. What if earth and sky were upside down? We would walk on the clouds and fly through the grass. What if fire was cold? In summer we would swim between flames.  
Two words, that’s all we need to start fantasize about everything that crosses our minds and it’s really a lot of stuff, because our brain? The most powerful weapon ever existed in all of the universe, we are lucky that no one can use it at maximum power.  
But I think we are diverting. So much with my unstoppable gab. Sorry.  
The thing is, even I can’t use all of my brain. I use a lot of it, but never all, I wouldn’t even know how to.

That isn’t the point. The point is “what if”.

So what if this time I wouldn’t be the only one telling you a story? You would hear two insane geniuses instead of one, but it would also mean something new would have happened.

What would have happened? Let’s try something like… what if two crazy aliens geniuses met two mad brilliant humans? Who are they and how they meet?

_Sorry to interrupt, my dear friend, but I think you are diverting once again._

I was getting there. Somehow. Do you mind take the short cut to get where I am trying to go?

_Not at all, dear. All right, the thing we are trying to explain put in simple words is: What if the Doctor and the Master got the chance to travel together and met John and Sherlock? Where with John and Sherlock we mean John Watson and Sherlock Holmes and with the Doctor and the Master we mean… the Doctor and the Master. I think you perfectly know who we are talking about, if not you better go right now._

We aren’t going to explain how they would meet?

_I think we are not, sorry._

But why? They want to know.

_I don’t doubt any of that but, darling, that would be a lot of complicated stuff about space, time, dimensions, parallel universes and timey wimey things that only you know and actually understand._

You have a point. Who were you when you were alive?

_I would tell you, but then I’d have to kill you._

Rude.

_No, don’t be offended, I would kiss you if I still had lips (and known where to kiss you)_

My circuits have blushed right now. But it seems like we are getting sidetracked together now, plus it’s not about the two of us, it’s about the four of them.

_Tch, they always get all the fun! But when you’re right, you’re right. Let’s just say that we are going to explain what would happen if those four ever met and that’s all. We won’t say how this would happen, it happens and that’s all. So…_

 

So, what if…

-correct me if I get it wrong, but what you are trying to tell us is that you are some kind of time traveler aliens that have technical difficulties with their time traveling spaceship (which looks like an old police box, by the way) and so you’ve landed and knocked on the first door you could find to ask for a cup of tea?-

the look on John’s face was between the “these guys really are hilarious, what the kids come up with nowadays for a joke… even if they don’t look so younger than me or Sherlock” and the “I can always distract them and then get my gun and that will be the end of this”.  
Before you ask, yes, John’s face can be _that_ expressive. Sherlock, on the other hand, was disquietingly silent, actually bathing in every little particular of those two bonkers.

–in fact the tea isn’t for us, but for my “spaceship”, which isn’t the correct name by the way, gathered that we will get back from where we came immediately- answered the pretty one in the long coat, for a moment John only thought “is my life cursed with repeated encounters with crazy, handsome blokes in a long coat or what?” before the other, the small, scary one, crossed his arms on his suited chest and snorted:-why don’t you just put a kettle in that faulty box? You wouldn’t have to burst in other people's house asking a cup of tea take away- the tall and pretty one, the Doctor was his name?, looked the other with an arched eyebrow:- first of all, the TARDIS has a dysfunction so clearly it doesn’t work, you twit, and second if we had to emergency land is all your fault. You and your brilliant idea of turning the TARDIS into a paradox machine!-

John was starting to believe those two were actually convinced of what they were saying and the thing wasn’t reassuring at all. And why the fuck now Sherlock started to pace the room looking at them and saying fucking NOTHING? John sighed and pinched the bridge of his nose, he had to keep calm, he knew and you can bet your granny’s dentures that he was trying, god help him, he was really trying but those two started quarrelling like a married couple and Sherlock was this far from taking out his magnifying glass and start collecting specimens. Of course he wasn’t seriously thinking they were real aliens, was he?  
He threw a desperate and questioning glance to his detective lover but it was spectacularly ignored.

Ok, enough with this insanity. He squared his shoulders and said loudly enough to be heard:-now you two shut up, for god’s sake, and introduce yourselves properly, ask us our names and state clearly what you want or you can get the bloody fuck out thank you very much- time traveler aliens or not, they both muted and even Sherlock tore his eyes from them to look at his little and peremptory lover that stood, all military mode on, in front of the two strangers that exchanged a look between them before the pretty one took a step forward and answered:-hello, I am the Doctor and this is the Master- which grimaced at the use of “this” to introduce him:-we are aliens, yes, time travelers too… and you are?-

John nodded briefly and looked once again at Sherlock, but the detective was still staring without saying a word, this time at John that, if he knew well that look (and he knew perfectly well), was forecasting some spectacular sex after these two got their tea or whatever, he cleared his throat, trying to put the thought apart, and answered: -I’m John Watson and that unbelievingly silent man is Sherlock Holmes. Now can you sit down and…- John arched an eyebrow and didn’t bother to end the sentence, since the two of them were gaping like fish: -what?- he asked:-you are kidding me- was all he got before the Doctor started walking around, a hand fisted in his hair (nice hair) and his voice shaking, the other just sighed and leaned against the open door muttering:-didn’t you read the number on the door?- 

Well, now they just knew who they were, his blog had gathered a discreet number of followers, but he never could have imagined a couple of aliens could read it and obviously the sarcasm in that thought was evident, but before he could say something, Sherlock, finally, switched on and said:-parallel universe- which made the Doctor stop pacing around and start staring at him:  
-how could you know?- he asked:-first there’s the thing that you are aliens- -oh, for fuck’s sake- ranted John:-really?-

Sherlock continued as naturally as if he was explaining one of his experiments:-yes, John, obvious. Time travelers you said, and that’s also true as showed by that particular device that is prodding from your coat pocket and that can’t be compared with any technology and could be alien too, but it looks like is a plausible item, from the future then. You mentioned before a “paradox machine” and that confirms we have to deal with a time machine and one that lately had been turned in its opposite, so it’s obvious that its functions are all heels over head and instead of traveling through space and time it traveled through dimensions. How can I say that? Because we don’t know you but you clearly know us and even if John’s blog is quite successful, I seriously doubt that aliens get the chance to read it, plus you look like two of us shouldn’t be here at all and I can assure you, it’s not me and John- he stopped and now the longing glance was from John. The erection too.

The Doctor smiled and said:-you did it for real-  
-of course, that’s what I do-  
-you truly are brilliant- Sherlock smirked smugly and conceded:-well, if you have to deal with all of this daily you can’t be that bad too-  
-but there’s something that you missed, isn’t it? There’s always something- the Doctor’s voice was playful and the two of them were advancing towards each other without even noticing, Sherlock frowned for a second and then admitted:-I can’t figure out why the tea- the Doctor grinned:-you couldn’t. the TARDIS, my “space ship”, is a sentient creature, tea is a vasodilator and it would have helped it rearrange itself-  
-I see-  
-no, you don’t-  
-oh, come on, just fuck already!- the Master said stopping the flirting, in fact they were just an inch apart, if they kept on a little longer they would have snogged right there, considering the eye sex they were exchanging. And John wasn’t pissed as he should have been, actually he was aroused, all that brilliance and so much brain were rising the temperature in his body and let’s face it: who wouldn’t like to see those two surprisingly dashing and hot aliens get at it? His raging erection was positively responding to it.

Silence stretched in the room, as if everyone was considering what the Master said (John surely was), until the Doctor said:-after this emergency landing we can’t adjust the TARDIS, not now, it needs to recover-  
-so now we wait- stated the Master, the Doctor looked at him and nodded, the other grinned and answered:-well then, you heard me before: fuck- the silence that followed wasn’t nearly as alarmed as it should have been, because everyone was in fact considering it.

Someone had to say something, hoping in Sherlock, that looked so genuinely intrigued, was useless, the Master had proposed the thing and the Doctor was already fidgeting at the idea, so it was on John’s head:-I don’t think it would be a great plan. I mean, we don’t know them and they are aliens, for pete’s sake! You can’t be serious, Sherlock-  
-John- the Master’s voice was soothing and his smile wolfish:-there’s nothing to fear, plus you want this as much as us and there’s no point in denying-  
-that doesn’t mean we have to…-  
-John they’re aliens, we could learn so much about them! When will this happen again? Aren’t you wondering how they have sex?- Sherlock was high, it was pointless reach out for him:  
-Doctor, you aren’t actually considering this, are you?- why was he asking such a thing to a stranger alien was a mystery to him as to us, believe me.

Obviously the answer of the Doctor was just a glance, he was so aroused that words were utterly useless: -John, believe me, you won’t regret this- said the Master, followed by Sherlock that looked pointedly to him and added:-but you’re right, John, it could be dangerous- those words always worked on him, especially when purred with desire by an overexcited Sherlock while he was fighting one of the most glorious erections of his life, so he just nodded and seated in his armchair. The Master chuckled and took the other seat, he then glanced at the Doctor that looked back and just nodded, John couldn’t have unseen the complicity that needs no words and recognize it as almost the same as it was between him and Sherlock.

The Master spoke then, except he wasn’t talking, he was just squeezing John’s hand and he could perfectly hear his voice, saying he hadn’t to worry, that his thoughts were safe, he wouldn’t peer around in his head, he would just make it possible for him to feel what the other two were going to feel. Ok, the alien part was definitely true.

Sherlock and the Doctor were still standing, looking at them and each other, Sherlock was putting his arms around the other when the Master cleared his throat:-oh, no, you two pretty little things are going to play by our rules- his voice was once again soothing but darkened by the voracity and the longing, John could feel a spark of desire run through all his body and he realized it really was coming from the two standing in front of them, the Master talked again:-first things first, Sherlock would you please take a step back?- he did as he was told:-good. Doctor, be a good boy and strip, thank you- a shiver ran through the Doctor’s body before he got out of his coat and tossed it on the sofa, he then bent to get rid of his shoes and oh, he was already playing because he had no need to do so but he was showing his body to Sherlock who understood and then grinned, obviously liking what he was seeing.

The Doctor peeled himself of every layer of clothes, with calculated slowness and meanwhile trying his best to look the most innocent he could and John almost felt bad when he realized that those brown puppy eyes and that face full of freckles, with that thin but extremely tempting mouth would have looked much better if he was crying, that knowledge surely came from the Master’s mind, but the sudden need to hit him was all John’s fault. When the Doctor was naked in front of them the thing became so much filthier, their gazes ran all over his body, thin but well built.

He stood there trembling lightly, from the cold or from excitement, they couldn’t tell. Sherlock could and provided the answer: both, but excitement a little more marked. -Sherlock, now you can touch him- said the Master and Sherlock’s long arms wrapped around the naked body of the Doctor, his pale hands sprawled on his back, the Doctor’s skin was darker and the contrast was exquisite, those hands stroked his back and shoulders while he closed the distance between their mouths, both were so pink and lavish, when John got a glimpse of tongue he almost moaned. He knew perfectly that the heat was rising and that both of them were damn good kissers, this “mental-link” thing was definitely good and intense.

Sherlock bit The Doctor’s lower lip, while his hand slipped in his hair “good” thought John “I would have done it too”, he moaned together with the Doctor, obviously both felt everything they did to each other and the thought was turning John terribly on.  
-Doctor, work Sherlock’s neck, he loves it- John heard his voice saying that and he could see out the corner of his eye the Master grin. The Doctor started kissing Sherlock’s jaw line and slowly he headed his kisses south, nibbling the sensitive skin of that long, pale neck and making Sherlock moan while he whimpered for the same reason. John knew Sherlock was very sensitive on his neck, but he never thought so much. He squirmed in the armchair and tried to recover the composure.

-Sherlock, undress- said the Master and he did as told, exposing that delicate skin and the long limbed body, John’s cock twitched in response and so must have happened in everybody’s pants. Thanks to that bloody link his mouth was watering at fourth intensity.  
-it looks like we have a rather interesting situation, because the Doctor is very, very, _very_ oral-  
-Sherlock too- answered John, how he wasn't drooling like a bull dog was a mystery:-sixty-nine, maybe?- he asked, the Master nodded:-sixty-nine will be. Did you hear? Come on- John wondered if they would do as told like that, on the floor, without a word of dissent.

He hadn’t to wonder anymore because the answer was yes, they swiftly knelt and Sherlock pushed the Doctor down on the floor, he put his knees at each side of the Doctor’s head, he stroked the other’s cock a couple of times before he started to lick it with experienced strokes of his tongue, the Doctor, on the other hand, licked his lips and swallowed Sherlock’s cock in one go. Everyone in the room moaned and hummed with pleasure, John was panting heavily, it was really like he was doing and receiving both the things and his mind was twisting between the sensations, in his mouth he could taste both the musky savors, one he recognized immediately, the other new but not unwelcome. Sherlock licked the other’s prick from root to head once again before swallowing it. John was impressed, both of them were performing some glorious blowjobs, how no one was already coming was an interesting question that he wouldn’t examine in that moment, not while the Doctor was circling his tongue in that way or while Sherlock was hollowing his cheeks just with the perfect pressure. He was melting in the armchair, so both Sherlock and the Doctor gave just a little scrape of teeth that sent shivers through four different spines and made four throats whimper.

Then the Master ordered:-Sherlock, finger him- the detective freed the other’s cock and slicked two of his fingers, while he went back on him, swallowing him again, he pushed one finger slowly into his entrance, the Doctor whimpered so lovely and parted his tights, the intensity of the thing was making John’s vision blur. Sherlock added the second finger and sped up the rhythm, reaching the other’s prostate and making him whine again, the Doctor was squirming, trying to push back on those fingers. John himself was wishing they could get to that part too.

-alright- said the Master, he was panting and his voice was hoarse:-let that little pliant bitch that is the Doctor get on his hands and knees so you can take him- Sherlock stopped and did as he was ordered, the Doctor got up and crawled in front of them, he looked at them directly in the eyes before he glanced up his shoulder to Sherlock, so turned on the detective moaned in response, he then parted his legs inviting him: -Doctor, get on your elbows- ordered John, the other did and he looked even more pliant, if that was even possible.  
And then Sherlock was there, pushing into him slowly, excruciatingly so, teasing everyone and himself too. The Doctor trembled while he was entering, but when the other settled he braced himself and clenched on him, the perfect combination of pleasure, pain and pressure.

He looked to them and asked, his voice shaking and high pitched:-do you like what you see?- John could have cracked a rock with his erection just for what he was seeing, the Master grinned:-it’s perfect, now you have to work for making us feel perfect too- the thing became even filthier when he said that because John actually realized that they were just giving orders, it was an exquisite, filthy game of power.

Sherlock started to move, what was happening was almost overwhelming, it would have been just by looking at it, but feeling everything was amazing, they could feel the wet, twitching warmness of a welcoming body just as well as a hard, barely slicked cock pushing steadily its way in and building a rhythm. John noted that the Master was clawing the armchair with his nails just like him, he sucked as many air as he could manage before telling Sherlock:-grab his hair and fuck him rough- and Sherlock did and god, Godzilla could have ripped the house open and they wouldn’t have stopped for a second.

He could see how Sherlock was drowning in everything, it was the most intense thing that both had ever felt, not only for the pleasure, but for the overflow of love that was filling their minds and bodies, for the Doctor and the Master it was normal, they were so old and used to be mentally linked, but they were just humans and a human brain could just tremble facing the intensity of a 900 years old love, a love that was so huge and kept changing form, it was boiling hot with passion, sweet and dripping like honey with feeling, it was sharp and cold with hate and unresolved questions, it was bleeding with regret, so much regret from both of them and it was covered in pitch black darkness from wanting. Something so big could have driven anyone crazy, but John wasn’t anyone, he wasn’t afraid of it and that was the only thing that kept him from falling into it.

But what about Sherlock? He wasn’t like John, emotions were really too much for him sometimes… Sherlock wasn’t anyone too, because the stream of feelings was washing on him and he wasn’t going to let it pull him away, he locked on the feeling of John’s love and sailed through it. But all that all together was something he never experienced or expected and so tears were falling down his face, dripping on the Doctor’s back.  
-maybe we should stop?- asked the Doctor, a bit concerned. John smiled:-no, it’s perfect- because he knew what he was going to do, he just knew how amazing his lover was, how stubborn, how strong, how human…

Sherlock kept on thrusting in his body while he lowered and whispered in his hear:-you are craving his forgiveness, aren’t you? You could do whatever he asks you, once it would have been unbearable because you wanted to be free, but when you lost him you understood how much you lost with him- he then bit his neck lightly, the Doctor moaned pushing back on him with more strength:-how… h-how could you know?-  
-I saw- answered Sherlock, breathless:-you would do anything to keep him with you, chain yourself to him, give him all you have, all of the earth, all your years of life… as an apology, the only time you really meant “sorry”… how I know? Because I’m the same- John smiled and blushed, no one ordered him to say all those things, but Sherlock was that stubborn.

The Master smiled lightly too, somewhere he could remember all the love they felt for each other and when the Doctor looked at him he sighed and looked back, obviously talking telepathically with him. He and Sherlock didn’t need to hear what they were saying, they had to talk together through their eyes, they weren’t telepaths but it was effective all the same.

Sherlock embraced the Doctor tight and put him in his lap so that the Master could see him, the Doctor looked at him once again before his eyelashes fluttered close and he started coming with a strangled cry. The combination of what they saw, the feelings, the sensations and the warmness made them come shortly after him that kept whining and moaning because of the link, even if he was totally spent, his body still twitching.

Sherlock rested his forehead between the Doctor’s shoulder blades, panting heavily, he braced the Doctor’s thin body and slid slowly out. After they cleaned themselves up and dressed again, John was sure he could sense the two of them still exchanging thoughts without a word and he felt happy for them because Sherlock was right: they needed to make things right despite all it was said and done in the past, even if he had no idea of what it was, because their love was so scary and hungry that it would have eaten them if left to starve.

-gathered some interesting data?- he asked Sherlock that grinned and answered:-you have no idea- the Doctor smiled:-and you’re not the only one. I have a lot to think about and hopefully a lot of time to do so-  
-talking of time- added the Master:-it was a pity we didn’t get to use that beautiful riding crop- Sherlock snorted and said:-yes, a real pity because I can guarantee it feels very, very good- John elbowed his lover lightly and muttered:-stop it-  
-what?-  
-the flirting, I can’t do much more for today, I need to lay down and sleep until tomorrow-  
-and we should really go- said the Doctor:-it was a pleasure- he embraced both Sherlock and John with a wide smile, as if they did some kind of magic to make his day. He then ran down the stairs clearly eager to start traveling immediately with the Master which stayed behind and looked at them, he cleared his throat and said:-thank you. Both of you-  
-we really didn’t…-  
-don’t, just let me thank you, it’s something I don’t do for humans… this _has_  to be a parallel universe because really- he smiled and slid his hands in his pockets:-I better go, now- he then turned and went down the stairs.

Both John and Sherlock ran to the window and looked as they approached their spaceship/box/thing, stopped on the door and kissed tenderly before entering and closing the door, some minutes later a strange noise filled the air and the police box started to fade until it disappeared. They stayed silent for a bit, then they looked at each other:-you think they were…?- started John  
-yes-  
-so we just had sex with two married aliens-  
-yes- they both started to giggle and then laugh. When they got the chance to breathe again John stated:-what you said to him… it was beautiful and you didn’t have to-  
-it just felt right… and I thought about what I said…- Sherlock was trying to say something important, John just knew:-tell me, Sherlock-  
-sorry if I sometimes am what I am- John put a finger on his lips and cut him off:-don’t you ever, ever try to say sorry for what you are, don’t you dare- Sherlock looked at him directly in the eyes and said without hesitation:-marry me, John- said man just froze on the spot and then smiled widely and tenderly:-yes-

-do you ever wonder if we have our counterparts in some parallel universe, Doctor?-  
-I don’t wonder, I know- the Master snorted and turned his head to look at the man in his arms, he kissed his forehead gently and held him more tightly:-are you fancying the idea of trying to get to them and have a “little chat”?- the Doctor asked grinning:-you really are a slut- both giggled:-I was having a serious moment here-  
-sorry, keep on-  
-well, I was wondering… what if they kept on parting from each other, chasing themselves all across the universe? What if they couldn’t say each other what we finally managed to say? What if they both died and regenerated?- the Doctor smiled warmly and kissed his lips:-they would have met again and again and again until they could finally say all those things and get back together once and for all- the Master smiled:-yes. You’re right-  
-what if you give me a second possibility and ask me to marry you again?-  
-would you marry me again?-  
-yes-


End file.
